From 12f3ca4cdb95b193af905a00e722a4dcb40b3de3 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Wed, 26 Apr 2017 19:45:00 +0000
Subject: Vendor import of llvm trunk r301441:
 https://llvm.org/svn/llvm-project/llvm/trunk@301441

---
 include/llvm/Support/FileSystem.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'include/llvm/Support/FileSystem.h')

diff --git a/include/llvm/Support/FileSystem.h b/include/llvm/Support/FileSystem.h
index 29515c231bc4..e3c5de7fbe64 100644
--- a/include/llvm/Support/FileSystem.h
+++ b/include/llvm/Support/FileSystem.h
@@ -116,7 +116,9 @@ inline perms &operator&=(perms &l, perms r) {
   return l;
 }
 inline perms operator~(perms x) {
-  return static_cast<perms>(~static_cast<unsigned short>(x));
+  // Avoid UB by explicitly truncating the (unsigned) ~ result.
+  return static_cast<perms>(
+      static_cast<unsigned short>(~static_cast<unsigned short>(x)));
 }
 
 class UniqueID {
-- 
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